We have recently discovered several novel compounds that inhibit hepatitis C virus (HCV) replication. One class of these compounds inhibits a key enzyme in the cholesterol biosynthesis pathway. Other inhibitors of the host cholesterol biosynthesis pathway also can suppress HCV replication in vitro. As intermediates in this pathway are important in the HCV lifecycle and must support both normal intracellular homeostasis and HCV infection, we therefore hypothesize that levels of important small molecule intermediates along the cholesterol biosynthetic pathway will be depleted in HCV infection. The specific aims of this proposal involve further defining the relationship between host lipid metabolism and chronic HCV infection: (1) Enhance the activity of and characterize the mechanism of action of our additional novel anti-HCV compounds. (2) Assess alteration of infectivity of HCV virions by statins and HMG-CoA synthase inhibitors. (3) Identify biomarkers for prognostication of outcome in chronic HCV infection using lipidomic assessment of HCV-infected cell lines, serum, and liver tissue. These studies will determine whether inhibitors of cholesterol biosynthesis decrease HCV virion infectivity in addition to suppressing HCV replication. They will also conduct exploratory studies aimed at discovery of novel prognostic biomarkers of HCV infection that could assist disease management. The examination of the mechanism of action of our anti-viral compounds can not only be used as a method to characterize key interactions and pathways critical to viral replication, but can be a productive means to the discovery of potential antiviral agents for the treatment of chronic HCV infection.